[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: [amsat-bb] Laser Satellite Comms



At 06:31 PM 3/1/99 -0500, Dr Thomas A Clark (W3IWI) wrote:
>it produces a diffraction limited "glint" reflection. ...
> ~1/40000 radians = 5 arc seconds. On the ground, the "spot
>size" will be about 10 meters in diameter.

Oops.  You're right.  My calculated spot size was too small, as I did the 
calc with straight geometry and forgot to consider diffraction.


>If the satellite is spinning at ~1 RPM, it will spinning at an angular
>rate of (3600 arcsec/degree)*(360 degrees/rev)/(60 sec/rev) =
>21600 arcsec/sec, so the 5 arcseconds "glint" is swept out by the
>mirror in 5/21600 = 230 microseconds.

Aren't you missing a factor of 2 here?  The spot spins around the disco 
twice as fast as the disco ball spins.  5/(21600*2) = 115 microseconds.

In any case, I agree with your conclusion.


----
Via the sarex mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe sarex" to Majordomo@amsat.org



AMSAT Top AMSAT Home